serial: max310x: register GPIO controller before adding UART ports

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The MAX310x exposes four GPIOs per UART port via an in-driver
gpio_chip. devm_gpiochip_add_data() used to run after the per-port
uart_add_one_port() loop, so a device-tree consumer referencing one of
the chip's own GPIOs (for example rs485-term-gpios = <&max310x 0 ...>)
could not resolve it during port registration: the GPIO provider it
waits for is the very driver still trying to register, and the lookup
returns -EPROBE_DEFER on its own provider, deferring probe forever.

Split the per-port setup into two passes around the gpio_chip
registration:

  1. Initialise per-port state - port struct fields, regmap binding,
     IRQ disable, work queues. The gpio_chip callbacks dereference
     s->p[i].regmap via to_max310x_port() and become callable as soon
     as the chip is visible to gpiolib, so every entry must be
     populated first.
  2. devm_gpiochip_add_data() - register the gpio_chip.
  3. Allocate a line, uart_add_one_port(), set_bit(), max310x_power().
     Keeping line allocation, registration and set_bit() together
     preserves the existing "bit set <=> port registered" rollback
     invariant that out_uart relies on.

Signed-off-by: Tapio Reijonen <tapio.reijonen@vaisala.com>
Link: https://patch.msgid.link/20260615-b4-max310x-rs485-dt-v3-1-7e79f064bdd7@vaisala.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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This commit is contained in:

Tapio Reijonen 2026-06-15 10:27:35 +00:00 • committed by Greg Kroah-Hartman

parent de96e8b27b

commit 25b51d1fd3

1 changed files with 33 additions and 21 deletions

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drivers/tty/serial/max310x.c

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